Bonding probe for bonded dual walled turbine components

ABSTRACT

A bonding probe is used for bonding a cover sheet to a core to form or repair a dual wall structure. The bonding probe includes a body, an attachment end at a distal end of the body, a head at an opposite end of the body, a tip extending from the head, and a cooling passageway. The attachment end couples the body to a resistance welder. The tip extends to form a proximate end of the body. The tip includes a contacting area having a predetermined three dimensional contoured surface. The contacting area aligns with a predetermined area of a three dimensional outer surface of a cover sheet of a dual walled structure. The cooling passageway provides a passageway for a flow of cooling fluid. The cooling passageway extends through the head, and into the tip.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of U.S. patent applicationSer. No. 16/807,107, filed Mar. 2, 2020, which is herein incorporated byreference in its entirety.

TECHNICAL FIELD

This disclosure relates to bonding probes for dual wall structures.Specific applications disclosed relate to combustion turbines and, inparticular, to complex geometry dual wall turbine component bonding withbonding probes.

BACKGROUND

Gas turbine engines generate large amounts of internal heat due tocombustion processes. As a result, engine components, such as turbineblades, may experience high thermal loads. The use of dual walledstructures in turbine engine components allows for higher operatingtemperatures.

Likewise, aircraft engines and aircraft themselves require low density,high strength structures, which are often created by using dual wallpanels. The disclosed system and method can be used to create a widevariety of dual walled structures using many different materials. Thesedual walled structures have value for turbine engine components,aircraft components, and other industrial structures such as heatexchangers, cooled structures, low density rigid structures, reactionmanifolding, and reaction plenums/chambers.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments may be better understood with reference to the followingdrawings and description. The components in the figures are notnecessarily to scale. Moreover, in the figures, like-referenced numeralsdesignate corresponding parts throughout the different views.

FIG. 1 is a cross-sectional view of an example of a gas turbine engine;

FIG. 2 illustrates an example of a portion of a three dimensionalcontoured dual wall structure;

FIG. 3 illustrates an example of a bonding system that includes abonding probe;

FIG. 4 illustrates an example of a bonding probe;

FIG. 5 illustrates an example of a bonding probe and a cut-away view ofa 3D contoured dual wall structure;

FIG. 6 illustrates an example of a bonding probe and a cut-away view ofa 3D contoured dual wall structure;

FIG. 7 illustrates another example of a bonding probe

FIG. 8 illustrates another example of a bonding probe and a cut-awayview of a 3D contoured dual wall structure;

FIG. 9 illustrates another example of a bonding probe and a 3D contoureddual wall structure;

FIG. 10 illustrates another example of multiple bonding probes and acut-away view of a 3D contoured dual wall structure;

FIG. 11 illustrates another example of multiple bonding probes and acut-away view of a 3D contoured dual wall structure;

FIG. 12 illustrates exemplary data fora bonding probe system;

FIG. 13 illustrates another example of data for a bonding probe system;

FIG. 14 illustrates another example of data for a bonding probe system;

FIG. 15 illustrates another example of data for a bonding probe system;

FIG. 16 illustrates exemplary data for a bonding probe system with shortbonding times;

FIG. 17 illustrates exemplary data for a bonding probe system with roomtemperature shear strength of 60% and 70% bonding heat;

FIG. 18 illustrates exemplary data for a bonding probe system and theeffects of the percentage of bonding heat on elevated temperature shearstress;

FIG. 19 illustrates exemplary parameters and arrangements on a coversheet of a bonding probe system for determining feasibility of NDEinspection;

FIG. 20 illustrates exemplary data of a bonding probe system forinvestigating scaling applied stress to rectangular electrodes; and

FIG. 21 illustrates exemplary data for trials of a bonding probe systemwith high load and utilizing Cu—Zr rectangular electrodes.

DETAILED DESCRIPTION

Described herein is a bonding probe for bonding dual wall structuressuch as turbine engine components, for example, blades, vanes, endwalls,and/or other similar components. An example turbine blade is disclosedto demonstrate the ability to create complex dual wall geometries. Thebonding probe includes a body, an attachment end, an insulator, a head,a tip, and a cooling passageway. The attachment end may be at a distalend of the body. The attachment end may couple to a resistance welder.The resistance welder is used for bonding, for example resistancebonding, diffusion bonding, and/or brazing/braze bonding. The insulatormay be coupled to the attachment end. The head may be coupled to theinsulator and may be at an opposite end of the body from the attachmentend. The tip may extend from the head to form a proximate end of thebody. The tip may include a contacting area, which may have apredetermined three-dimensional (3D) contoured surface. The 3D contouredsurface of the contacting area may align with a predetermined area of a3D contoured outer surface of a 3D cover sheet of a dual walledstructure. The 3D contoured surfaces of the contacting area of the tipand the outer surface of the cover sheet may be highly contouredsurfaces that align with each other.

The tip may be electrically coupled to the resistance welder via theattachment end. The contacting area may have a three dimensional (3D)contoured surface that may match or follow the 3D contour of the outersurface of the cover sheet. The contacting area may abut against theouter surface of the cover sheet opposite an inner surface of the coversheet abutting a pedestal of the dual walled structure. The contactingarea may be equal to or greater than a surface area of the pedestal. Thecontacting area may include a surrounding peripheral edge, which definesa perimeter of the contacting area. The perimeter of the contacting areamay correspond to a predetermined area of the 3D contoured outer surfaceof the 3D contoured cover sheet.

The cooling passage may provide a path for a flow of a cooling fluid.The cooling passage may extend from the attachment end, through thehead, and into the tip. The cooling passage may include a tip inletpassage, a contacting area cavity, and a tip outlet passage. Thecontacting area cavity may fluidly connect the tip inlet passage and thetip outlet passage. The contacting area cavity may be substantiallyparallel to the contacting area. During operation of the resistancewelder, the cooling fluid in the tip inlet passage may be cooler thanthe cooling fluid in the contacting area cavity. The cooling fluid inthe tip outlet passage may be warmer than the cooling fluid in thecontacting area cavity.

An aspect of the system includes aligning a pedestal, and/or series ofpedestals and other features, of the core of a dual wall structure, suchas a turbine blade, with a cover sheet of the dual wall structure sothat the cover sheet and pedestal are in contact with each other. Abonding probe is placed in contact with the cover sheet in apredetermined location. A tip of the bonding probe may include a threedimensional contoured surface to follow and align with a threedimensional contoured portion of the cover sheet at the predeterminedlocation. An inner pedestal probe is placed on the dual wall turbinestructure in another predetermined location such that a conductiveelectric path is formed from the cover sheet probe to the inner pedestalprobe through the cover sheet and pedestal of the dual wall structure.The cover sheet probe and inner pedestal probe apply a localizedpressing force to the pedestal and the cover sheet at the respectivepredetermined locations. Electric power is applied along the conductiveelectric path to heat a junction between the cover sheet and pedestal.The flow of electricity generates heat which is used to form ametallurgical bond either by melting the interface thus creating a bond;diffusing the material of the components together to form a diffusionbond; or by using a preplaced interface material that either diffusesinto both faces and creates a diffusion bond or melts and creates abraze joint. The heated junction may cool and fixedly join, or bond, thecover sheet to the core via the pedestal.

One unique feature of the bonding probe described herein may be that thecooling passageway may extend into the tip of the bonding probe.Alternatively or additionally, the contacting area cavity may extendalong and/or in close proximity to the contacting area of the tip.Because of these features, the cooling passageway may cool thecontacting area and/or the outer surface of the cover sheet to minimizeor eliminate deformation of the cover sheet and/or outer surface of thecover sheet.

Another interesting feature of the bonding probe may be that a materialof the head and/or tip of the bonding probe may have a higher degree ofmalleability and/or elasticity than a material of the cover sheet. Thismay allow for more surface area contact between the contacting area ofthe tip and the outer surface of the cover sheet due to the tipconforming to the 3D surface of the cover sheet. Additionally oralternatively, this may prevent plastic deformation of the cover sheetduring the bonding process. This may also eliminate or minimizedeformation of the cover sheet by the bonding probe or bonding process.

Another interesting feature may be that the cooling passageway mayincrease the rigidity and strength of the bonding probe and/or tip.Additionally or alternatively, the flow of cooling fluid may increasethe life of the bonding probe.

FIG. 1 shows an example of a gas turbine engine 100. In some examples,the gas turbine engine 100 may be used for flight operations, forexample to supply power to and/or provide propulsion of an aircraft. Theterm aircraft, for example, may include a helicopter, an airplane, amissile, an unmanned space vehicle, or any other similar device.Alternatively or in addition, the gas turbine engine 100 may be used inother vehicles or in an industrial application. Industrial applicationsmay include, for example, an energy application, a power plant, apumping set, a marine application, a weapon system, a security system, aperimeter defense or security system.

The gas turbine engine 100 may include an intake section 120, acompressor section 160, a combustion section 130, a turbine section 110,and an exhaust section 150. Operation of the gas turbine engine 100 mayinclude receiving fluid, such as air, from the intake section 120. Thefluid may travel along the direction D1. The fluid may travel from theintake section 120 to the compressor section 160, where the fluid iscompressed. The compressed fluid may be mixed with fuel in thecombustion section 130. The mixture of fuel and fluid may then be burnedin the combustion section 130 creating combustion gases. The combustiongases, or combustion fluid, may then flow from the combustion section130 to the turbine section 110 to extract energy from the combustionfluid. The energy from the combustion fluid may cause a shaft 140 of aturbine 114 in the turbine section 110 to rotate. The shaft 140 of theturbine 114 may in turn drive the compressor section 160. After passingthrough the turbine section 110, the combustion fluid may be dischargedfrom the exhaust section 150.

During operation of the gas turbine engine 100, the fluid, such as air,may pass through the turbine section 110. The turbine section 110 maycontain a plurality of adjacent gas turbine blades 112 coupled to arotor disk. It is understood that gas turbine blades and vanes are oftenreferred to as airfoils. In an example, the blades 112 may be bonded tothe rotor disk to form a mechanically robust, monolithic component. Theblades 112 may, alternatively, be fabricated separately from the rotordisc and the conventionally joined to the rotor disc. The blades 112 maybe made of a rigid material, for example, the blades 112 may include ametal alloy. Alternatively, the blades 112 may include a heat resistantsuper alloy composition, for example, a nickel based or cobalt basedcomposition. Alternatively, the blades 112 may include a ceramicmaterial, such as a ceramic-matric composite (CMC) material. At least aportion of the blades may be formed, for example, through a castingprocess.

In the turbine section 110, the combustion fluid may pass betweenadjacent blades 112 of the turbine 114. The combustion fluid passingover the blades 112 may cause the turbine 114 to rotate. The rotatingturbine 114 may turn the shaft 140 in a rotational direction D2, forexample. The blades 112 may rotate around an axis of rotation, which maycorrespond to a centerline X of the turbine 114 in some examples. Inaddition, or alternatively, in other examples, the blades 112 may bepart of a static vane assembly in the turbine section 110 of the gasturbine engine 100.

FIG. 2 illustrates an example of three dimensional (3D) contoured dualwalled airfoil structure in the form of a portion of blade 112 and/orvane. The features and functionality described with respect to FIG. 2may also be typical of other dual walled structures having 3D contouredsurfaces, such as other 3D contoured dual walled gas turbine enginecomponents, so the description herein should not be construed as limitedto turbine blades. The example blade 112 is illustrated as a dual wallturbine blade. The illustrated portion of the blade 112 includes a core210 and a cover sheet 220. The cover sheet 220 and core 210 may form anairfoil of the blade 112 when bonded together. The core 210 and thecover sheet 220 may, for example, be metallurgically bonded as describedherein. The core 210 and cover sheet 220 may be made of rigid materials,for example, a metal alloy. Alternatively, the core 210 and cover sheet220 may comprise a heat resistant super alloy composition, for example,a nickel based or cobalt based composition. The core 210 and cover sheet220 may be made of the same or different materials.

The blade 112 may have a highly contoured shape. For example, the blade112 may be three dimensionally contoured. The core 210 and/or coversheet 220 may have corresponding highly contoured surfaces, for example,predetermined three dimensional contoured surfaces in order to realizethe desired shape of the blade 112. A three dimensional contouredsurface refers to a surface defined by an X, Y, and Z axis. A threedimensional contoured surface is pre-defined by a cloud of points wherein addition to surface variation of X and Y coordinates, Z coordinatesmay also vary from point to point of the three dimensional surface inorder to form a predetermined three dimensioned contour. Thus, a threedimensional contoured surface may have a predetermined varying depthcomponent (e.g. Z coordinates). In contrast, a two dimensional surfacemay be defined by only an X and Y axis because Z coordinates on thesurface do not change or change only slightly with insignificant orminimal variation due to non-predefined distortions of the surface, suchas surface roughness. A two dimensional surface may have a predeterminedconstant depth, or substantially constant predetermined depth thatvaries due to the presence of surface roughness. Thus, as describedherein, predetermined three dimensionality of a contoured surface doesnot include surface roughness.

The core 210 may be formed, for example, through casting. The core 210may have a discontinuous surface. The core 210 may include a leadingedge 214, a trailing edge 218, a pressure side 234, and a suction side232. The core 210 may be hollow and include a cooling channel 240 thatextends through at least a portion of the length of the blade 112. Inthe illustrated example, the core 210 includes multiple cooling channels240 in an airfoil core of the core 210. In other examples, additional orfewer cooling channels 240 may be present. The cooling channels 240 maybe defined by one or more interior walls 242 of the core 210. Thecooling channels 240 may be supplied with fluid, such as secondary airprovided by the gas turbine engine. The core 210 may include one or morepedestals 212. The pedestal 212 may be a raised surface feature of thecore 210. The pedestals 212 may be raised from the interior wall 242 ofthe core 210. The pedestals 212 may be raised from the opposite surfaceof the interior wall 242 with respect to the cooling channel 240 so asto extend away from the interior wall 242.

FIG. 2 and the discussion herein focuses on bonding the cover sheet 220and the pedestal(s) 212 using the system and methods described.Alternatively, or in addition, the bonding performed as discussed anddescribed herein may occur between the pedestal(s) 212 and the core 210.Thus, in some examples, the pedestals 212 may be coupled with the core210 or the cover sheet 220 by other than operation of the system. Forexample, the pedestals 212 may be integrally formed with the core 210such as by casting, additive manufacture, bonding, or other joiningtechniques of the core 210 and the pedestals 212 to provide a relativelylow resistance junction, or no junction, between a respective pedestal212 and the core 210 resulting in a highly conductive path for electriccurrent. In alternative examples, the bonding performed with the systemas discussed and described herein may be between the three dimensionalcontoured surface(s) of the pedestal(s) 212 and the core 210, and thebonding of the pedestal(s) 212 and the cover sheet 220 may also beaccomplished to form the relatively low resistance junction, or nojunction, between the cover sheet 220 and the pedestal(s) 212. Anadvantage of omitting the bond between the pedestals 212 and the coversheet 220, for example, when the dual walled structure is used as aturbine blade or vane, is to avoid placing a bond created by the systemin a region that experiences higher heat during the operation of aturbine engine. It should nevertheless be understood that bonding of thethree dimensional highly contoured surface of the pedestal(s) 212 to thecover sheet 220, the core 210, or both, may be performed as describedherein.

The core 210 may include one or more pedestals 212, for example, thecore 210 may include approximately 1,000 pedestals on each side of thecore 210. The pedestals 212 may constitute surface regions of thediscontinuous surface of the core 210. The core 210 may include flowchannels 216. The flow channels 216 may be adjacent to the pedestals212, such that the pedestals 212 separate the flow channels 216. Theflow channels 216 may be positioned between the core 210 and the coversheet 220 when the core 210 and cover sheet 220 are bonded together. Theflow channels 216 may be sealed when the core 210 and cover sheet 220are bonded together, thus enabling the ability of guiding fluid througha predesignated circuitous path. Fluid, such as air, may flow throughthe flow channels 216 of the core 210.

The core 210 may include a network of pedestals 212 and flow channels216. The pedestals 212 and the flow channels 216 may form one or morepatterns of the pedestals 212 on the core 210. The interior wall 242 mayinclude inlet ports 244 that penetrate the interior wall 242. The flowchannels 216 may be in fluid communication with the cooling channel 240via the inlet ports 244. The pedestals 212 and the flow channels 216 maybe formed, for example, through a casting process. Alternatively or inaddition, the pedestals 212 and the flow channels 216 may be formed, forexample, through a machining process.

The arrangement of pedestals 212 and flow channels 216 shown in FIG. 2is only one example of a possible configuration, and is not intended tobe limiting. The pedestals 212 and the flow channels 216 may formstraight, linear paths with sharp angles. Alternatively, the pedestals212 and flow channels 216 my form curved, nonlinear paths.

The pedestals 212 may vary in shape. The pedestals 212 may be elongatedsuch that the pedestals 212 continuously extend from the trailing edge218 to the leading edge 214 of the core 210 to form the flow channels216 there between. For example, the pedestals 212 may each be in theshape of a raised rib or rectangle shaped platform. Additionally oralternatively, the pedestals 212 may be in any intermixed arrangement ofshapes and/or patterns to achieve the functional results desired of thefinal component design In one example, each rectangular pedestal 212 maycontinuously extend horizontally across the surface of the core 210,between the leading edge 214 and the trailing edge 218. For example, thepedestals 212 may be positioned parallel to each other and be spaced apredetermined distance from each other. The spacing between the parallelpedestals 212 may be the same. Alternatively the pedestal 212 may extendin differed directions with respect to each other and/or be variablyspaced from each other to form the flow channels 216. Alternatively oradditionally, the pedestals 212 may continuously extend vertically fromthe radially outward end of the core 210 to the radially inward end ofthe core 210. The vertically extending pedestal 212 may cross or connectwith one more pedestals 212 extending horizontally 212.

The pedestals 212 may connect to each other, that is, one pedestal 212may connect to an adjacent pedestal 212. The pedestals 212 may beshapes, for example circles or squares, that do not connect to eachother, that is one pedestal 212 does not contact another pedestal 212 toprovide a flow channel 216 there between. The distance between thepedestals 212 or the spacing of the pedestals 212 from each other mayform a pattern of the pedestals 212 on the core 210. The pattern mayinclude pedestals 212 uniformly spaced from each other to form arepetitive pattern, or pedestals 212 with varying spacing from eachother. Additionally or alternatively, the pattern may include pedestals212 of uniform or varying shapes.

The pedestals 212 may include a surface area 250 disposed towards thecover sheet 220. The surface area 250 of the pedestals 212 may be acontinuously connected surface area 250 of multiple pedestals 212 inexample configurations where one pedestal 212 is connected to anotherpedestal 212. The surface area 250 may be defined by a surroundingperipheral edge 213 of the pedestal 212. The peripheral edge 213 may bea continuous edge surrounding multiple connected pedestals.Alternatively or additionally, the pedestals 212 may be discontinuousand/or unconnected, with each pedestal 212 having a respectiveperipheral edge 213 defining a respective surface area 250. The surfacearea 250 may abut an inner surface 224 of the cover sheet 220. Thesurface area 250 may be the surface of the pedestals 212 opposite theend of the pedestal 212 abutting the interior wall 242 of the core 210.The surface area 250 may be planar. Alternatively, the surface area 250of the pedestals 212 may be contoured.

The surface area 250 of the pedestals 212 may be uniform or may bevariable to align with an interior surface of the cover sheet 220 forpurposes of bonding at least some of the pedestals 212 to the coversheet 220. The surface area 250 may conform to the cover sheet 220. Forexample, the cover sheet 220 and the surface area 250 may be curved witha predetermined mathematically defined curvature such that the suctionside 232 and/or the pressure side 234 of the airfoil is formed by thecover sheet 220 when bonded to the core 210. The surface area 250 of thepedestal 212 may match the corresponding mathematically definedcurvature of the surface of the cover sheet 220 such that the coversheet 220 maintains the predetermined shape when bonded to the pedestal212, or the cover sheet 220 assumes the predetermined mathematicallydefined curvature when bonded to the pedestal 212. Accordingly, thesurface areas 250 may be one or more predetermined shapes orconfigurations to achieve desired bonding. The surface area 250 of thepedestal 212 may be highly contoured. For example, the surface area 250may be a three dimensional contoured surface formed with predeterminedX, Y and Z coordinates. The 3D contour of the surface area 250 maycorrespond with the 3D contour of an area of cover sheet 220 that thesurface area 250 contacts. The three dimensional contour of each of thesurface areas 250 may differ and/or be unique. The cover sheet 220 maybe three dimensionally contoured such that the surface area 250 of eachpedestal 212 varies and/or is different among different pedestals 212.In other words, the three dimensional contoured inner surface of thecover sheet 220 and the three dimensional contoured surface of thepedestal 210 may provide uniform intimate contiguous contact therebetween. Alternatively or in addition, as discussed herein, the bondingof three dimensional contoured surfaces may occur between thepedestal(s) 212 and the core 210.

The cover sheet 220 may include an outer surface 222 and the innersurface 224. The inner surface 224 may be the surface of the cover sheet220 disposed towards the core 210. The inner surface 224 of the coversheet 220 may abut the pedestals 212. The inner surface 224 may becoupled to pedestals 212 when the cover sheet 220 is bonded with thecore 210 and/or the pedestals 212. The cover sheet 220 may bemetallurgically bonded to the pedestals 212 as described herein. Thecover sheet 220 may be bonded to the pedestals 212 at the surface area250. The cover sheet 220 may be bonded to the core 210 such that thecover sheet 220 covers the pedestals 212 and flow channels 216. Thecover sheet 220 may create a fluid tight seal with the pedestals 212such that fluid flows through the flow channels 216 of the core 210. Thecover sheet 220 may form a continuous outer layer of at least part ofthe blade 112. Additionally, an area of the cover sheet 220 may bebonded to another area of the cover sheet 220. For example, the coversheet 220 may be bonded to itself at the leading edge 214 and/or thetrailing edge 218 of the core 210. The outer surface 222 may be thesurface of the cover sheet 220 opposite the inner surface 224. The outersurface 222 and/or inner surface 224 may be planar or contoured. Forexample, the outer surface 222 and/or inner surface 224 may be a threedimensional contoured surface. The three dimensional contour of theouter surface 222 and the three dimensional contour of the inner surface224 may be oppositely contoured surfaces, whereas a convex outer surfaceand a concave inner surface are oppositely contoured surfaces. Forexample, a portion of a sheet with a convex outer surface would have acorresponding, oppositely contoured concaved inner surface. The coversheet 220 may include outlet ports 226 that penetrate the cover sheet.Fluid, such as air, may discharge from the flow channels 216 via theoutlet ports 226 and into the turbine section 110 (FIG. 1).

FIG. 3 illustrates an example of a bonding system 300 including abonding probe. The bonding system 300 may include controller circuitry340, a resistance welder 350, a cooling system 360, and a press system380. The resistance welder 350 may be used for bonding, for exampleresistance bonding, diffusion bonding, or braze bonding/brazing. Aresistance bond may result in, for example a resistant weld or weldnugget. The resistance welder 350 may include a power supply 352, afirst bonding probe 310, which is hereinafter referred to as a coversheet probe 310, and a second bonding probe, which is hereinafterreferred to as an inner pedestal probe 320. In other examples, the coversheet probe 310 and/or the inner pedestal probe 320 may also be refer toas bonding probes. The resistance welder 350 may be electrically coupledto the cover sheet probe 310 and the inner pedestal probe 320. Theresistance welder 350 and the press system 380 may cooperatively operatein combination with the controller circuitry 340 and/or the coolingsystem 360. The cover sheet probe 310 may include a tip 312 extendingfrom a head 316. The inner pedestal probe 320 may include a tip 324extending from a head 322.

The cover sheet probe 310 may be, for example, a source electrode or asupply electrode configured to supply a voltage and current.Alternatively, the inner pedestal probe 320 may be some other form ofconnection to the core 210, for example, a clamp. The tip 312 of thecover sheet probe 310 and the tip 324 of the inner pedestal probe 320may be made out of a conductive material, for example an alloy. Thealloy, for example, may include one or more of copper, cobalt, tungsten,nickel, or another similar material to, for example, tailor a balancebetween thermal conductivity and compliance/creep. The material may beselected based on the desired properties of the tip 312. The material ofthe tip 312 may be selected such that the tip is deformable. Forexample, the material of the tip 312 may be selected to be moredeformable than the cover sheet 220 in order to minimize and/oreliminate the formation of a dent, other undesirable surface feature, inthe cover sheet 220 resulting from the bonding process. Additionally oralternatively, the material for the cover sheet 220 may be selected, forexample, to be less deformable than the tip 312. For example, thematerial of the tip 312 may have a greater yield strength than thematerial of the cover sheet 220. The tip 312 of the cover sheet probe310 and the tip 324 of the inner pedestal probe 320 may be made of thesame or different materials.

The parameters used for conducting the process may be adjusted toproduce the type of bond desired (e.g. resistance bond, braze bond, ordiffusion bond). The controller circuitry 340 may control operationparameters 342 of the bonding system 300. The operation parameters 342may be used by the controller circuitry 340 to manage and control thebonding process. The operation parameters 342 may, for example, includepressing force 370, location 372, electrical current 346, electricalvoltage 348, cooling fluid temperature 376, sensor circuitry 378 and/orany other operational parameters used to manage and control the bondingprocess. The operation parameters 342 may include hardware or somecombination of hardware and software to perform the described functions.For example, the controller 340 may control the voltage and currentlevels of electrical power supplied by the resistance welder 350 to thecover sheet probe 310. In this example, the controller 340 may controlthe electrical current 346 and/or the electrical voltage 348 supplied tothe cover sheet probe 310 based on predetermined settings, user enteredvalues, or sensed feedback provided from the sensor circuitry 378. Theoperation parameters 342 may vary depending on the operation, but may,for example, be set to a pressing force 370 of 1779.29 Newtons, for aspecific pedestal location 372, an electrical current 346 of 1630 Amps,and a cooling fluid temperature 376 of room temperature. The pressureand temperature sensor circuitry 378 and/or any other operationalparameters may also be used to control the bonding process. Theresistance welder 350 may, for example, be a Miyachi Unitek 875 DualPulse Stored Energy Power Supply. Parameters of the resistance welder350 may vary depending on the materials, conditions, operation, andother variables, but may, for example, be set to the parameters in FIG.12.

The controller circuitry 340 may include at least one processorcircuitry 344 in communication with memory storage circuitry 374. Atleast some of the functionality of the controller circuitry 340 asdescribed herein may be performed with the processor circuitry 344. Forexample, the processor circuitry 344 may access and store predeterminedsettings for at least some of the operation parameters 342 in memorystorage circuitry 374. In addition, or alternatively, otherfunctionality of the bonding system 300 may be provided by other partsof the controller circuitry 340. For example, the controller circuitry340 may control the magnitude of voltage and a flow of current throughthe cover sheet probe 310 and the inner pedestal probe 320. Thecontroller circuitry 340, for example, may control the supply of voltageand current to the cover sheet probe 310 such that an intermittent pulseof electric power is supplied to the cover sheet probe 310. The durationand magnitude of the intermittent pulse of electric power may becontrolled by the controller circuitry 340. A practical application ofthis capability, for example, is interpreting Non-Destructive Testing(NDT) or Non-Destructive Evaluation (NDE) data to determine the numberof pedestals or area requiring bonding repair and selecting theappropriate cover sheet probe 310 based on this data and the associatedpresent bonding parameters 342.

Portions of the cover sheet 220 that abut a pedestal 212 and/or eachpedestal 212 may have a unique predetermined three dimensional contouredsurface. Each portion, area, or sub-area of the three dimensionalcontour of the cover sheet 220 and/or pedestal 212 may correspond to aspecific cover sheet probe 310. Alternatively, or in addition, eachportion area, or sub-area of the three dimensional contour of the of thecover sheet 220 and/or each pedestal 212 may correspond to only onecover sheet probe 212. Thus, in some examples, the three dimensionalcontour of each cover sheet probe 212 may correspond to only onepedestal 212 or portion of the cover sheet 220. The system 300 maychoose the correct cover sheet probe 212 and/or set the parameters forcompletion of bonding based on the area or sub-area needing repair orinitial bonding.

The sensor circuitry 378 may receive and process electric signals fromexternal sensors, such as current, voltage, pressure, temperature, andlocation sensors providing electric signals indicative of the respectivesensed parameters to the controller circuitry 340 via the sensorcircuitry 378. Alternatively or additionally, the sensor circuitry 378may receive and process signals from externally processed data such as(NDT/NDE) sensors or results. The sensed parameters may be used by thecontroller circuitry 340 to control the bonding system 300 in the mannerdescribed.

The sensors may detect resistance, current, bonding pressure, andtemperature, which may be provided as feedback and/or feed forwardand/or monitoring signals to the controller circuitry 340. Based on thesensed signals from the sensors, the controller circuitry 340 mayprovide close-loop adjusted parameters.

The tip 312 of the cover sheet probe 310 may be placed in contact withthe outer surface 222 of the cover sheet 220. For example, the tip 312may abut the outer surface 222 of the cover sheet 220. The tip 312 ofthe cover sheet probe 310 may be three dimensionally contoured to followor match a portion of the three dimensional contoured outer surface 222of the cover sheet 220. Additionally the tip 312 may be threedimensionally contoured to follow the 3D contoured surface area 250 ofthe pedestal 212 in contact with the 3D contoured inner surface 224 ofthe cover sheet 220. For example, the three dimensional contouredsurface of the tip 312 may have the same three dimensional contour ofthe inner surface 224 of the cover sheet 220. Additionally oralternatively, the outer surface 222 of the cover sheet 220 may have thesame three dimensional contour as the surface 250 of the pedestal 212.As the inner surface 224 and the outer surface 222 of the cover sheet220 may be oppositely contoured, the surface 250 of the pedestal 212 andthe tip 312 may be oppositely contoured such that the outer surface 222,inner surface 224, pedestal 212, and tip 312 all have matching threedimensionally contoured surfaces. The matching three dimensionalcontoured surfaces of the tip 312, outer surface 222 of the cover sheet220, the inner surface 224 of the cover sheet 220, and the pedestal maycreate a path of lower relative resistance at a first junction 328between the tip 312 and the outer surface 222 than at a second junction330 of the inner surface 224 and the surface area 250 of the pedestal212.

The three dimensional contour of the tip 312 may allow for the distancebetween tip 312 of the cover sheet probe 310 and the outer surface 222to remain constant along the first junction. The distance between theinner surface 224 of the cover sheet 220 and the surface area 250 of thepedestal 212 along the second junction may be larger than the distanceof the first junction 328. Alternatively or additionally, tip 312 of thecover sheet probe 310 and/or the tip 324 of the inner pedestal probe 320may be made of different material(s) than the cover sheet 220 and/orcore 210. The material(s) of the tips 312 and/or 324 may have a higherconductivity than the material(s) of the core 210 and/or cover sheet 220of the blade 112. For example, the tips 312 and/or 342 may be made ofcopper, or another similar material, and provide a lower resistance thanthe material(s) of the core 210 and/or cover sheet 220, for example anickel or cobalt based super alloy. The material(s) of the tips 312/324may also conform to a contacting surface better than the material(s) ofthe core 210 and/or cover sheet 220. Because of the material differencebetween the tip(s) and the blade 112 and/or because the distance may belarger between the inner surface 224 and the pedestal 212 than thebetween the tip 312 and the outer surface 222, the resistance along aconductive electrical path 314 may be highest at the second junction330. Thus, the second junction 330 may be a localized maximumtemperature junction of the conductive electric path 314, by design.

The tip 312 of the cover sheet probe 310 may include a surface areafootprint that corresponds to the surface area footprint of the pedestal212 on the opposite side of the cover sheet 220 from the tip 312. Thesurface area of the tip may also be referred to as a contacting area.Thus, for example, a square or circular shaped footprint of a 3Dcontoured surface of the tip 312 may correspond in shape to a square orcircular shaped footprint of a 3D contoured surface of a pedestal. Inaddition, or alternatively, the surface area footprint of the tip 312contacting the outer surface 222 of the cover sheet 220 may be equal toor greater than a surface area footprint of the pedestal 212 contactingthe inner surface 224 of the cover sheet 220. Thus, for example if thetip 312 of the cover sheet probe 310 includes a 3D contoured surface ofa 3.175 mm square, or an area of 10.08 square mm, the 3D contouredsurface of the pedestal 212 contacting the inner surface 224 of thecover sheet 220 is equal to or less than 10.08 square mm. In an example,the surface area of the tip 312 may be larger than the surface area of apedestal 212 such the 3D contoured surface of the tip 312 extends beyondone or more peripheral edges of the pedestal 212 by up to 30% of thetotal distance between the pedestal 212 and neighboring pedestals.Because the surface area of the tip 312 is larger than the surface areaof the pedestal 212, there may be less resistance between the tip 312and the outer surface 222 of the cover sheet 220 than between the innersurface 224 of the cover sheet 220 and the pedestal 212. This maycontribute to the resistance along the conductive electrical path 314being highest at the second junction 330. Alternatively or in addition,as discussed herein, the bonding of three dimensional contoured surfacesmay occur between the pedestal(s) 212 and the core 210, wherein thehighest resistance along the conductive electrical path 314 is betweenthe pedestal 212 and the core 210.

The tip 324 of the inner pedestal probe 320 may be in contact with apart of the dual wall turbine blade 112 such as the core 210. Forexample, the tip 324 of the inner pedestal probe 320 may abut a surfaceof the core 210, such as against one or more of the pedestals 212.Alternatively, the tip 324 may abut the interior wall 242. The tip 312of the cover sheet probe 310 may abut the cover sheet 220 opposite anarea where one of more of the pedestals 212 abuts the inner surface 224of the cover sheet 220. The controller circuitry 340 may control thepress system 380 using the tips 312 and 324 to exert the pressing force370 against the cover sheet 220 and the dual wall turbine blade 112,respectively. The pressing force 370, for example, may be predetermined,user entered or based on parameters sensed by external sensors. Thepressing force 370, for example, may be localized to one predeterminedarea of the airfoil without applying force to other areas of theairfoil. The cover sheet 220 may be temporarily affixed to the dual wallturbine blade 112 by the pressing force 370 or some other retentionprocess. The cover sheet 220 may be affixed to the dual wall turbineblade in a predetermined location or positioned in preparation forbonding.

The tip 312 of the cover sheet probe 310 and the tip 324 of the innerpedestal probe 320, when contacting the cover sheet 220 and core 210respectively, may create a conductive electrical path 314. Electricitymay flow along the conductive electrical path 314 from the cover sheetprobe 310 to the inner pedestal probe 320. Electricity may flow alongthe conductive electrical path 314 through at least part of the dualwall structure 112. Electricity may flow along the conductive electricalpath 314 through at least part of the pedestal 212. Electricity may flowthrough the cover sheet 220 and the core 210. The flow of electricitymay heat the second junction 330 between the cover sheet 220 and thepedestal 212. The second junction 330, for example, may be createdbetween the cover sheet 220 and one or more pedestals 212. The heatgenerated by resistance in the second junction 330 to the flow ofelectricity may create a heated area 332 at the second junction 330. Theheated area 332 may cool and fixedly couple the cover sheet 220 and core210. The heated area 332 may cool to form, for example, a resistancebond or a spot bond. A resistance bond may be, for example a resistanceweld. A spot bond may be, for example, a spot weld. The bonding, forexample, may be localized. The heated area 332 may cool to form, forexample, a bond nugget, for example, a weld nugget. The bonding may belocalized to the predetermined surface area 250 (FIG. 2) of one or moreof the pedestals 212. Alternatively or in addition, as discussed herein,the bonding of three dimensional contoured surfaces may occur betweenthe pedestal(s) 212 and the core 210.

Additionally, the inner pedestal probe 320 may contact the core 210 at athird junction 334 with a predetermined contact surface area. A ratio ofthe contact surface areas of the third junction 334 (between the innerpedestal probe 320 and the core 210) and the first junction 328 (betweenthe cover sheet probe 310 and the outer surface 224 of the cover sheet220) may be predetermined. For example, the inner pedestal probe 320 maycontact a larger surface area of the blade 112 than the cover sheetprobe 310. By having a larger contact surface area, the third junction334 may have a lower relative resistance than other junctions along theconductive electrical path 314. The contact ratio may allow for amaximum temperature junction along the conductive electrical path 314 tobe at the second junction 330 between the inner surface 224 of the coversheet 220 and the pedestal 212. Alternatively or additionally, thesecond junction 330 may be a maximum temperature junction as compared tothe first junction 328 or third junction 334 of a respective pedestal212 corresponding area of cover sheet 220. The first junction 330,second junction 330, and third junction 334 may be along the conductiveelectrical path 314.

The cooling system 360 may include one or more pumps 362, a heatexchanger 364, a temperature sensor 366, and supply lines 368. Thecooling system 360 may circulate a cooling fluid 378. The cover sheetprobe 310 may include a cooling passageway 318. The cooling passageway318 may extend through the cover sheet probe 310. The cooling passageway318, for example, may extend through the tip 312 of the cover sheetprobe 310. The supply lines 368 may couple to the cooling passageway 318such that cooling fluid may be circulated through the cover sheet probe310 and/or the tip 312 of the cover sheet probe 310. The cooling fluid378 may flow through the supply lines 368 to the cover sheet probe 310.The cooling fluid 378 may cool the cover sheet probe 310 and bycirculating through the cover sheet probe 310 and return to the heatexchanger 364. The returning cooling fluid 378 may be cooled by the heatexchanger 364 and then again be circulated through the cover sheet probe310.

The flow of the cooling fluid 378 may be driven by one or more pumps 362included in the cooling system 360. The temperature sensor 366 may oneor more temperature sensors disposed to sense the temperature of thecooling fluid 378 circulating in the cooling system 360, such as forexample in the flow path before or after the cover sheet probe 310. Thetemperature sensor 366 may sense the temperature of the cooling fluid378 being supplied to and/or received from the cover sheet probe 310.The controller circuitry 340 may increase, decrease, or maintainconstant the cooling of the cover sheet probe 310 using the coolingsystem 360 based on feedback from the temperature sensor 366. Forexample, the controller 340 may increase or decrease the flow of thecooling fluid 378 by controlling flow rate with the one or more pumps362. Alternatively, or additionally, the controller 340 may increase ordecrease the rate at which the cooling fluid 378 is cooled by the heatexchanger 364.

The press system 380 may include a pressing force generator 382, one ormore pressure sensors 384, and one or more proximity sensors 386. Theproximity sensor 386 may be used by the press system 380 to locate orotherwise position the cover sheet probe 310 in a predetermined area ofthe cover sheet 220. One application of this, for example, is in theform of interpreting NDT and/or NDE data and locating a specific coversheet probe 310 or bank of cover sheet probes 310. Another application,for example, may be operational sequencing of bank cover sheet probes310 to successfully manufacture a highly contoured component.Additionally, the proximity sensor 386 may be used to locate the innerpedestal probe 320 to a predetermined area of the core 210. For example,the proximity sensors 386 may be used to locate the inner pedestal probe320 to one of the pedestals 212 and the cover sheet probe 310 to an areaof the cover sheet 220 in contact with the corresponding pedestal 212.The pressing force generator 382 may generate a predetermined amount offorce to be applied by the cover sheet probe 310 to the cover sheet 220.For example, the cover sheet probe 310 may apply a predetermined force,measured in Newtons, to the cover sheet in a predetermined direction,such as perpendicular to the outer surface of the cover sheet. Forexample, an example of this is interpretation of NDT and/or NDE resultsand selecting a proper cover sheet probe 310 from a bank of cover sheetprobes 310 and setting the force appropriately. Another example isproper sequencing of bank cover sheet probes 310 and adjusting thepressure and parameters based on the specific cover sheet probe 310required to manufacture a highly contoured 3D component.

In one example, the bonding system 300 may include a two-axis X-Y stagewith a servo control system built to locate defect areas for resistancebonding repair. The bonding system 300 may have a machine accuracy of0.00508 mm and a travel distance of 60.96 cm×101.6 cm. The X-Y-Z systemmay be integrated with resistance bonding system and with the NDE/NDTsystem, inspection of images, and digital data.

The pressing force generator 382 may generate a corresponding pressingforce. The pressure sensors 384 may be used to detect to a magnitude offorce being applied to the cover sheet 220 by the press system 380.Feedback from the pressure sensors 384 may be used by the bonding system300 to adjust the amount of force generated by the pressing forcegenerator 382. The applied force may create an electric conductive pathof relatively less resistance between the probe 310 and the cover sheet220. One interesting feature of the bonding system 300, for example, isthat the system 300 may use resistance pre-heating and long post-bondinghold time, with a cover sheet probe 310 having a predetermined 3Dcontoured surface design, and plated bonding interfaces.

The press system 380 may be controlled to balance heating of the heatedarea with cooling of the tip 312 of the cover sheet probe 310 to avoidindentation of the cover sheet 220 due to excessive temperature of thetip 312 in combination with the contacting pressure being asserted onthe cover sheet 220.Aditionally or alternatively, the press system 380may be controlled to also balance the material properties of the coversheet 220 and/or tip 312 such that any plastic deformation of the coversheet 220 from the bonding process is decreased or eliminated.Additionally or alternatively, the tip 312 may be a two-way shape-memoryalloy such that the tip 312 may deform during the bonding process andreturn to a predetermined shape, for example, a predetermined 3Dcontour, upon cooling after the bonding process is complete.Alternatively or additionally, the tip 312 may deform to match thepredetermined 3D contour of the cover sheet 220. The tip 312 may deformto match the contour of the cover sheet 220 during the bonding process,for example, due to the heat generated and the pressing force exerted bythe press system 380. The tip 312 may deform to match the predetermined3D contour of the cover sheet 220 due to changes in the contour of thecover sheet 220 and/or the tip 312 that results from, for example, themanufacturing process. For a given part there may be multiple uniqueprobes 310, the control system may perform selection of the cover sheetprobe 310 selection based on NDT, NDE, and/or other sequencing input,select the correct probe 310 and select the proper parameters based onthe probe 310 and results to be achieved.

All features and functionality discussed with reference to FIGS. 1-3 areapplicable to the following embodiments and examples unless otherwiseindicated.

FIGS. 4 and 7 illustrate examples of a bonding probe 410. The bondingprobe 410 may be an example of one or more of the cover sheet probe 310of the bonding system 300 (FIG. 3). The bonding probe 410 may,alternatively or additionally, be an example of one or more of the innerpedestal probes 320 of the bonding system 300 (FIG. 3). The bondingprobe 410 may include a tip 412. The tip 412 may be one example of tip312 (FIG. 3.) Thus, for brevity, the discussion with respect to FIGS.2-3 will not be repeated and it should be understood that all describedfeatures and functionality are applicable to FIGS. 4 and 7 unlessotherwise indicated.

The tip 412 may include a contacting area 414. The contacting area 414may include the surface area of the tip 412, as described elsewhere. Thetip 412 and/or the contacting area 414 may be three dimensionallycontoured to correspond to the three dimensional contoured surface area250 of one or more of the pedestals 212 (FIG. 2). Alternatively oradditionally, the tip 412 and/or the contacting area 414 may be threedimensionally contoured to match the surface area 250 of one or more ofthe pedestals 212. Alternatively or additionally, the tip 412 and/or thecontacting area 414 may be three dimensionally contoured to match thethree dimensional contour of the outer surface 222 of the cover sheet220 (FIG. 2).

Portions of the cover sheet 220 that abut a contacting area 414 and/oreach contacting area 414 may have a unique predetermined threedimensional contoured surface. Each portion, area, or sub-area of thethree dimensional contour of the cover sheet 220 and/or contacting area414 may correspond to a specific cover sheet probe 310. Each portion,area, or sub-area of the three dimensional contour of the cover sheet220 and/or contacting area 414 may correspond to a specific 3D contouredsurface of a pedestal 212. Alternatively, or in addition, each portionarea, or sub-area of the three dimensional contour of the of the coversheet 220 and/or each contacting area 414 may correspond to only onecover sheet probe 310. Thus, in some examples, the three dimensionalcontour of each cover sheet probe 310 may correspond to only onepedestal 212 or portion of the cover sheet 220. Accordingly, a locationon the cover sheet of each portion, area, or sub-area of the threedimensional contour of the cover sheet 220 may be mapped or otherwiseassociated with at least one specific bonding probe 410 by the system300 (FIG. 3). The system 300 may choose the specific cover sheet probe310 and/or set the parameters for completion of bonding based on thecorresponding associated location of the portion, area or sub-areaneeding repair.

The cover sheet probes 310 and the inner pedestal probe 320 may have thesame or different shapes and/or contours. Alternatively or additionally,the bonding probe 410 of the inner pedestal probe 320 may be shaped, forexample, such that the inner pedestal probe 320 can access and contact apredetermined area of the core 210. For, example, the inner pedestalprobe 320 may be shaped such that the inner pedestal probe 320 canaccess the cooling channel 240 and/or area of the interior wall 242. Theinner pedestal probe 320 may be shaped, for example, such that the innerpedestal probe 320 can access the core 210 already bonded to the coversheet 220.

The three dimensional contour and conformity of the tip 412, and theparameters 342 of the bonding system 300, are chosen to balance thecooling aspect and tip compliance such that plastic deformation of thecover sheet 220 is minimized or absent. Alternatively or additionally,the tip 412 material and cover sheet 220 material may be selected inorder to minimize deformation of the cover sheet 220. For example, thetip 412 material may be selected have a greater degree of elasticityand/or malleability than the cover sheet 220 material such that the tip412 will deform before, or with greater deformation than, the coversheet 220. The materials of the tip 412 and cover sheet 220 may beselected in accordance with the expected range of heating and coolingtemperatures of the tip 412 and/or other parameters of the bondingsystem 300, such as pressing force, in order to minimized deformation ofthe cover sheet 220.

Additionally or alternatively, the tip 412 may be a two-way shape memoryalloy such that the tip 412 may deform in a predetermined way, such asto assume a predetermined heated 3D contour during the bonding processand return to a predetermined shape, for example, a predetermined cool3D contour, upon cooling after the bonding process is complete. Thedeformation in a predetermined way by the tip 412 may, for example, besimilar to deformation of the cover sheet 220 during the bonding processin order to maintain a desired level of contiguous contact between theabutting 3D contoured surfaces during transitory heating and cooling andcorresponding deformation. Such contiguous contact may providetemperature management to avoid or minimize cover sheet deformation.

Cover sheet deformation may result in stress risers that can initiatecracks. The probe tips 412 may be manufactured, for example, by brazing,diffusion bonding, and/or ALM such that cooling liquid can flow into thedistal tips 412 of the shaped bonding probe 410 to maximize cooling. Theshaped probes 410 allow power selection of the bonding system 300 tobalance probe compliance and cover sheet deformation to minimize oreliminate cover sheet deformation. The probes 412 may be designed basedon the NDT and/or NDE inspection results of defects to perform thisrepair in automated settings. The software that controls the system maybe linked to code, in one example, code written in Labview, to link datacoming from ultrasonic and/or other operations related to the NDE and/orNDT.

The surface area 250 and/or the outer surface 222 may be matched toallow for better surface contact and therefore conductivity between thesurface area 250 and the bonding probe 410 and/or the outer surface 222and the bonding probe 410. Contouring to match the tip 412 with thesurface of the cover sheet 220 may create a relatively low resistanceconductive electrical path between the tip 412 of the bonding probe 410and the outer surface 222 of the cover sheet 220. The conductiveelectrical path at the first junction 328, between the tip 412 and theouter surface 222, may be relatively low resistance with respect to theresistance of the conductive electrical path at the second junction 330of the inner surface 224 and one of the pedestals 212. The highestresistance along conductive electric path 314 (FIG. 3) may be at thesecond junction 330. The magnitude of the pressing force 370 may alsolower the resistance between the tip 412 and/or contacting area 414 andthe outer surface 222. The bonding probe 410 may allow localizedbonding. For example, the bonding may be welding, such as resistancewelding or spot welding. The localized bonding may be used, for example,for repairs. For example, the repairs may repair a breach in the coversheet 220 or to correct localized defects in the dual wall turbine blade112. The defects may be found, for example, through inspection, such asradiographic, ultrasonic or thermographic inspection. The thermographicinspection may be accomplished with, for example, an infrared (IR)camera and flash lamps.

FIG. 4 illustrates an example of a bonding probe 410. The bonding probe410 may include a body 411. The body 411 may include an attachment end430 at one end of the body 411 and bonding end 417 at another end of thebody 411. The bonding end 417 may be at an opposite end of the body 412from the attachment end 430. The bonding end 417 may include a head 416and a tip 412. The head 416 may be a frustoconical shaped member that istapered toward the tip 412 to provide a diminishing cross-sectionalarea. The tip 412 may extend outwardly away from the head 416. The tip412 may have planar side walls 413 extending to a proximate end 420 ofthe body 411, forming the contacting area 414. The planar side walls 413may extend from an end of the head 416 opposite the end of the head 416coupled to a neck joint 424. The head 416 may be coupled to an insulator422 via the neck joint 424. The planar side walls 413 may extendsubstantially perpendicular from the end of the head 416 or at an angleto the head 416. The planar side walls 416 may terminate at thecontacting area 414. The contacting area 414 may be a circular,triangular, rectangular or any other predetermined shaped surface, andmay be dimensioned to correspond to at least a portion of the surfacearea 250 of a pedestal 212 (FIG. 2).The tip 412 may be electricallyconductive and electrically coupled to the resistance welder 350 via theattachment end 430 of the bonding probe 410. As previously discussed thetip 412 material may be selected to have a greater degree of elasticand/or malleability than the cover sheet 220.

The planar side walls 413 may define a peripheral edge 415. Theperipheral edge 415 may include the edges formed by the intersection ofthe planar side walls 413 and the contacting area 414. The peripheraledge 415 may define a perimeter of the contacting area 414. Thus, thecontacting area 414 may be the interior area defined by peripheral edge415, wherein the peripheral edges 415 continuously surround thecontacting area 414. As discussed herein, the contact area 414 maycorrespond to a predetermined area of the 3D contoured surface area ofthe cover sheet 220, or to a 3D contoured surface area 250 of a pedestal212. The peripheral edge 415 defining the contacting area 414 may alignin a predetermined arrangement with the peripheral edge 213 of thepedestal 212. Accordingly, in examples, the peripheral edge 415 may alsodefine the peripheral edge 213 and corresponding surface area 250 of thepedestal 212.

FIG. 5 illustrates an example of a bonding probe 310 and a cut-away viewof a three dimensional (3D) contoured dual wall structure. The surfacearea of the tip 312 and/or the contacting area 414 of the tip 412 (FIG.4) may be larger than the surface area of a pedestal 212 such the 3Dcontoured surface area of the tip 312 and/or contacting area 414 (FIG.4) extends beyond one or more peripheral edges of the pedestal 212 (FIG.2) by a dimension Y. Dimension Y, for example, may be up to 30% of thetotal distance between the pedestal 212 and neighboring pedestals,dimension X. Alternatively or additionally, a peripheral edge of tip 312and/or the peripheral edge 415 defining the contacting area 414 (FIG. 4)may align with a predetermined area of the cover sheet 220, wherein thethree dimensional contoured surface of the surface area of tip 312and/or of the contacting area 414 defined by the peripheral edge 415(FIG. 4) corresponds to a predetermined three dimensionally contouredarea of outer surface 222 of the cover sheet 220. The predeterminedthree dimensionally countered area of the outer surface 222 maycorrespond to a specific pedestal 212 to abut a corresponding opposinginner surface 224 area of the cover sheet 220.

Referring back to FIG. 4, the head 416 and the tip 412may becooperatively manipulated to allow the bonding probe 410 to access andabut otherwise unreachable areas of the outer surface 22 or the core 210to perform bonding. In other examples, the contacting area 414 may beone or more of the planar surfaces of the tip 412. The tip 412 may be anelectrically conductive material through which electrical power suppliedby the resistance welder 350 may flow. The head 416 may be anon-conductive heat dissipating member surrounding the tip 412. In otherexamples, the head 416 may be an electrically conductive materialthrough which electrical power supplied by the resistance welder 350 mayflow.

The head 416 may be coupled with the insulator 422 by the neck joint424. The insulator 422 may be formed of a non-conductive material thatdissipates heat generated by current flowing through the bonding probe410. The neck joint 424 may fixedly couple the insulator 422 and head416. The neck joint may be an electrically conductive material throughwhich electrical power supplied by the resistance welder 350 may flow.The insulator 422 may also include a portion of the cooling passageway318 (FIG. 3) included in the bonding probe 410.

The bonding probe 410 may also include an attachment end 430. Theattachment end 430 may include a threaded member 432, a flange 434 and abolt 436. The attachment end 430 may couple the bonding probe 410 to theresistance welder 350, for example, via the threaded member 432. Theattachment end 430 may electrically couple the tip 412 to the resistancewelder 350. The bolt 436 may couple the insulator 422 to the attachmentend 430. The insulator 422 may be coupled to the flange 434 via the bolt436. The threaded member 438 may be coupled to the flange 434 oppositethe bolt 436. The threaded member 432 may threadably couple withstructure such as an arm, strut or other member through which thepressing force 370 may be exerted on the bonding probe 410 by thepressing system 380. (FIG. 3) The threaded member 432 may be formed toinclude at least one aperture 438 through which the cooling fluid mayflow into the cooling passageway 318 (FIG. 3) included in the bondingprobe 410. In an example, the aperture 438 may include an inlet and anoutlet to provide circulation through the bonding probe 410. The flange434 may include a conical shaped end 440 to create a liquid tight sealwith structure to which the threaded member 432 is detachably coupled.The bolt 436 may provide a grip location for rotationally removing andinstalling the bonding probe 410 using a tool such as a wrench.

FIG. 6 illustrates an example of a bonding probe and a cut-away view ofa 3D contoured dual wall structure. The cooling passageway 418 mayextend through the base of the bonding probe 410, for example, throughaperture 438 formed in the threaded member 432, through bonding probe410, and into the tip 412. The cooling passageway 418 may extend throughthe tip 412. The cooling passageway 418 may extend, at least in part,through threaded member 432, flange 434, bolt 436, insulator 422, neckjoint 424, and/or head 416 to reach the tip 412. In other examples, thecooling passageway 418 may extend partially through the bonding probe410 to the tip 412. For example cooling fluid may be supplied into thebonding probe 410 via an aperture in the flange 434, bolt 436, insulator422, neck joint 424, and/or head 416 to flow into the tip 412.

The cooling passageway 418 may include a contacting area cavity 510, atip inlet passage 520, and a tip outlet passage 530. The contacting areacavity 510 may be disposed in the tip 412 in close proximity to thecontacting area 414 such that cooling fluid flowing through thecontacting area cavity 510 cools the contacting area 414, cover sheet220, and/or the first junction 328 between the contacting area 414 andthe outer surface 222 of the cover sheet 220 by convection. Thecontacting area cavity 510 may extend substantially parallel to thecontacting area 414. The contacting area cavity 510 may contain a largervolume of cooling fluid than the passageway 418. For example, across-sectional area of the contacting area cavity 510 may be greaterthan twice a cross-sectional area of the passageway 418. In anotherexample, a cross-sectional area of the contacting area cavity 510 may besmaller and/or larger than a cross-sectional area of the passageway 418.Cooling fluid may flow at a much faster rate through the contacting areacavity 510 than through the passageway 418, for example, as a result ofthe difference in cross sectional areas of the passageway 418 and thecontacting area cavity 510. In another example, the internal surface ofthe contacting area cavity 510 may have special cooling features thatprovide additional cooling benefit, for example groove, recesses, and/orother formations that increase the surface area in contact with thecooling fluid in the contacting area cavity 510. In exampleconfigurations, the contacting area cavity 510 may be wider in diameteror have a different cross sections shape than other areas of the coolingpassageway 418. The contacting area cavity 510 may, for example, have awidth that extends the majority of the width of the contacting area 414such that the contacting area cavity 510 aligns with and cools the widthof the contacting area 414. The contacting area cavity 510 may extendalong the contacting area 414 such that the contacting cavity 510follows the 3D contoured surface of the contacting area 414.

Cooling fluid may flow into the contacting area cavity 510 via the tipinlet passage 520. Cooling fluid may flow out of the contacting areacavity via the tip outlet passage 530. The tip inlet passage 520 and/orthe tip outlet passage 530 may extend through the bonding probe 410 andinto the tip 412. Cooling fluid may flow through the tip inlet passage520 to deliver cooling fluid into the contacting area cavity 510. Thecooling fluid flowing through the tip inlet passage 520 may be cooler intemperature than cooling fluid in the contacting area cavity 510 and/orthe tip outlet passage 530. Cooling fluid may flow from the tip inletpassage 520 to the contacting area cavity 510 such that the coolingfluid in the contacting area cavity 510 absorbs heat from the tip 412.Cooling fluid flowing through the tip outlet passage 530 may be warmerin temperature than cooling fluid in the contacting area cavity 510and/or the tip inlet passage 520 due to the heat absorbed by the coolingfluid in the contacting area cavity 510 and/or the tip inlet passage520.

The tip inlet passage 520 and/or the tip outlet passage 530 may extendinto the tip 412 substantially parallel to a planar side wall 413 of thetip 412. Additionally or alternatively, the tip inlet passage 520 and/orthe tip outlet passage 530 may form a non-linear path extending throughthe tip 412. For example, the tip inlet passage 520 and/or the tipoutlet passage 530 may extend in a serpentine path through the bondingprobe 410 and/or tip 412. Alternatively or in addition, the tip inletpassage 520 and/or the tip outlet passage 530 may, for example, extendthrough the tip 412 in alternating directions, such that a flow ofcooling fluid through the tip inlet passage 520 and/or the tip outletpassage 530 changes directions one or more times within the tip 412. Thetip inlet passage 520 and/or the tip outlet passage 530 may changedirections such that cooling fluid flows substantially parallel to thecontacting area cavity 510 one or more times within the tip 412 atdifferent distances from the contacting area 414. The tip inlet passage520 may extend into the tip 412 from the head 416 in closer proximity toa first planar wall 413 of the tip than the tip outlet passage 530.Additionally or alternatively, the tip outlet passage 530 may returninto the head 416 from the tip 412 in closer proximity to a secondplanar wall 413 of the tip than the tip inlet passage 520. The firstplanar wall and the second planar wall may be opposite planar walls 413.

The flow of cooling fluid through the tip 412 may help minimize and/orprevent the formation of a dent in the cover sheet 220 during thebonding process. Additionally or alternatively, the flow of coolingfluid through the cooling passage 418 may extend the life of theelectrode 410. A portion of the cooling passage 418 within the tip 412may be formed through an additive manufacturing process, for example,additive layering manufacturing (ALM). Alternatively or additionally,the contacting area 414 and planar side walls 413 may be formed througha subtractive manufacturing process. For example, the contacting area414 and planar side walls 413 may be machined by removing material froma portion of stock material. The tip 412 and/or cooling passage 418 maybe formed through ALM and the planar side walls 413 and/or contactingarea 414 then machined from the ALM material. The cooling passage 418formed within the tip 412 may extend the life of the bonding probe 410.For example, the non-linear path formed by the cooling passage 418within the tip 412 may increase the rigidity and/or strength of thebonding probe 410.

FIG. 7 illustrates another example of a bonding probe 410. The bondingprobe 410 of this example includes a bonding end 417. In this example,bonding end 417 may include the tip 412 may and the head 416.Additionally or alternatively, the bonding probe 410 may not include thecooling passageway 418. For example, the tip 412 may be solid withoutany internal passageways for cooling fluid 378. The surface of thebonding probe 410 may be a curved surface, for example a dome shapedsurface. The contacting area 414 may be disposed on any portion of thesurface of the curved tip 412. The surface of the contacting area 414may be three dimensionally contoured to match the surface area 250 ofthe pedestal 212 and/or the outer surface 222 of the cover sheet 220.The head 416 may be a solid rigid shaft configured to be fixedly held ina compression fitting, such as a chuck. The compression fitting may beincluded in a structure such as an arm, strut or other member throughwhich the pressing force 370 may be exerted on the bonding probe 410 bythe pressing system 380. (FIG. 3)

FIGS. 8 and 9 illustrate examples of a bonding probe and a threedimensional (3D) contoured dual wall structure. The bonding system 300may be used to initially bond the cover sheet 220 and the core 210 toform a structure, such as a new airfoil. The bonding system 300 maysimultaneously abut a corresponding tip 312 to each predetermined areaof the cover sheet 220, such that each predetermined area of the coversheet 220 aligns and abuts with one of the pedestals 212. The bondingsystem may then, at substantially the same time, bond the cover sheet220 to the pedestals 212 at each second junction 330 of the cover sheet220 and pedestals 212, such that a conductive electrical path 314 isformed between each tip 312 and respective pedestal 212, wherein eachsecond junction 330 of the cover sheet 320 and core 210 may be arespective maximum temperature junction. Each conductive electrical path314 may include a first junction 328, second junction 330, and thirdjunction 334. Additionally, or alternatively, the bonding system 300 maybe used to selectively repair an area of a pre-existing airfoil, such asto create or repair a bond between a single second junction 330 orpreselected second junctions 330 of one of the pedestals 212 and thecorresponding areas of the cover sheet 220. The bonding system may abutthe tip 312 of the cover sheet probe 310 to a single area of the coversheet 220, wherein the area of the cover sheet 220 abuts to one of thepedestals 212. The bonding system 300 may abut the tip 324 of the innerpedestal probe 320 to a predetermined area of the core 210 correspondingto the pedestal 212. The bonding system 300 may then create a bond atthe single predetermined second junction 330 of the pedestal 212 and thecover sheet 220. Accordingly, in a repair mode, the processor circuitry340 may selectively energize only some of the cover sheet probes 310where a bonding repair is desired. Alternatively or in addition, asdiscussed herein, the bonding of three dimensional contoured surfacesmay occur between the pedestal(s) 212 and the core 210.

FIG. 8 illustrates another example of a bonding system probe and acut-away view of a 3D contoured dual wall structure. One or more bondingprobes 310, which will hereinafter be referred to as cover sheet probe310 may each include a head 316. The head 316 may include a plurality oftips 312. For example, multiple tips 312 may be coupled to the samecover sheet probe 810 and/or head 316, as illustrated. The plurality oftips 312 may correspond to a pull plane 710 (FIG. 9). The plurality oftips 312 may form a pattern of tips 312, wherein the pattern of tips 312may correspond a pull plane 710 (FIG. 9). The core 210 may include aplurality of the pedestals 212. The pedestals 212 may form a pattern ofthe pedestals 212. One or more of the tips 312 may abut against theouter surface 222 of the cover sheet 220. For example, one or more oftips 312 may abut against the outer surface 222 such that each one ofthe tips 312 match to one of the pedestals 212. The pattern of thepedestals 212 may match the pattern of tips 312 such that a location ofeach one of the tips 312 on the outer surface 222 corresponds to alocation of each one of the pedestals 212 on the core 210. For example,the cover sheet probe 310 may include a tip 312 for each of the secondjunctions 330 of the cover sheet 220 and core 310.

The cover sheet probe 310 and/or the inner pedestal probe 320 mayinclude any of the features and functionality of the bonding probe 310and bonding probe 410 discussed with reference to FIGS. 3-7. Inaddition, previously discussed features and functionality may be usedinterchangeably or cooperatively with the cover sheet probe 310 and/orinner pedestal probe 320, unless otherwise indicated. Thus, for purposesof brevity, the discussion will focus more on differences with theseexamples. As illustrated in FIG. 8, the cover sheet probe 310 may havemultiple tips 312 extending from a single bonding probe 310, and themultiple tips 312 may be connected to a resistance welder from a singleattachment end 430 (FIG. 4) of the bonding probe 310. Alternatively oradditionally, the cover sheet probe 310 may include multiple heads 316,wherein each head corresponds to a predetermined area of the cover sheet220. Alternatively or additionally, multiple tips 312 may extend awayfrom a single head 316. Each tip 312 may correspond to a different areaof the cover sheet 220. Multiple heads 316 and/or tips 312 may beconnected to a single attachment end 430 (FIG. 4) of cover sheet probe310. Alternatively or additionally, the inner pedestal probe 320 mayinclude multiple tips 324 extending from head 322. Each tip 324 maycontact the core 210 in a different area. The inner pedestal probe 320may have multiple heads 322 with a tip 324 extending from each head 322.Alternatively or additionally, inner pedestal probe 320 may havemultiple tips 324 extending from a single head 322.

FIG. 9 illustrates another example of a bonding probe and a 3D contoureddual wall structure. The cover sheet probe 310 may include any of thefeatures and functionality of the bonding probe 310 and/or bonding probe410 discussed with reference to FIGS. 3-8. In addition, previouslydiscussed features and functionality may be used interchangeably orcooperatively with the cover sheet probe 310, unless otherwiseindicated. Thus, for purposes of brevity, the discussion will focus moreon differences with these examples. One cover sheet probe 310 mayinclude multiple tips 312 extending from head 316. In addition,previously discussed features and functionality may be usedinterchangeably or cooperatively with the cover sheet probe 310, unlessotherwise indicated. Thus, for purposes of brevity, the discussion willfocus more on differences with these examples. The one cover sheet probe310 may include tips 312 for only a portion of the second junctions 330.For example, one or more pull planes 710 of the core 210 may bedetermined based on the 3D contour of the core 210 and blade 212, forexample, based on the degree of pull angle or draft built into the core210 and/or blade 212. The pull planes 710 may corresponded to a portionof the 3D surface of the core 210, wherein a plurality of pedestals 212may be packaged within one pull plane 710. The plurality of pedestals212 and/or a pattern of pedestals 212 may define the pull plane 710.Alternatively or additionally, the surface area 250 of the plurality ofpedestals 212 may define the pull plane 710. The 3D contoured surface ofthe cover sheet probe 310 may correspond to the pull plane 710, whereineach one of the contacting areas 414 (FIG. 4) of the tips 312 of asingle cover sheet probe 310 corresponds to a respective pedestal 212within the pull plane 710. The bonding system 300 may include coversheet probes 310 each corresponding to a respective pull plane 710 ofthe core 210, wherein each probe 310 includes a plurality of tips 312,the contacting area 414 (FIG. 4) of the tips 312 corresponding to thepull plane 710. Each tip 312 may correspond to a respective pedestal 212and the three dimensional contoured surface of the tip 312 correspondingto the three dimensional contoured surface of the pedestal 212.

In a new manufacturing operating mode, the tips 312 may simultaneouslybe energized while abutted to the outer surface 222 such that thebonding system 300 simultaneously creates a bond at each second junction330 of the cover sheet 220 and core 210. Additionally or alternatively,in a repair operating mode only selected of the tips 312 may beenergized while abutted to one or more second junctions 330 such that abond is created at only a portion of the second junctions 330 of thecore 210 and cover sheet 220. Selection of the tips to energize may beuser selected, or may be selected based on testing to identify existingbonds in need of repair.

FIG. 10 illustrates another example of multiple bonding probes and acut-away view of a 3D contoured dual wall structure. The bonding probe310 and/or the bonding probe 410 may include any of the features andfunctionality of the bonding probe 310 and bonding probe 410 discussedwith reference to FIGS. 3-9. In addition, previously discussed featuresand functionality may be used interchangeably or cooperatively with thebonding probe 310 and/or the bonding probe 410, unless otherwiseindicated. Thus, for purposes of brevity, the discussion will focus moreon differences with these examples. Bonding probe 410 maybe an innerpedestal probe 320 (FIG. 3) One or more of the inner pedestal probes 410may be placed on the core 210 to allow for conductive electrical paths314 (FIG. 3) to form between the inner pedestal probe 410 and each tip312 of the cover sheet probe 310. For example the inner pedestal probe410 may be placed at a predetermined area of the core 210 to allow forbonds to be created simultaneously at each second junction 330 of thecore 210. Alternatively or additionally, the inner pedestal probe 320may be placed, for example, in an internal passage of the core 210corresponding to one or more of the pedestals 212 to allow for bonds tobe created at only a portion of the second junctions 330 of the core210. For example, the inner pedestal probes 320 may be inserted in tothe cooling channel 240 or flow channel 216. For example, the innerpedestal probe 320 may be inserted into the cooling channel 240 andcontact a portion of the interior wall 242. The inner pedestal probe 320may contact a portion of the interior wall 242 corresponding to one ormore of the pedestals 212. Alternatively or in addition, as discussedherein, the bonding of three dimensional contoured surfaces may occurbetween the pedestal(s) 212 and the core 210.

FIG. 11 illustrates still another example of multiple bonding probes anda cut-away view of a 3D contoured dual wall structure. The cover sheetprobe 310 and/or the inner pedestal probe 320 may include any of thefeatures and functionality of the bonding probe 310 and bonding probe410 discussed with reference to FIGS. 3-10. In addition, previouslydiscussed features and functionality may be used interchangeably orcooperatively with the cover sheet probe 310 and/or inner pedestal probe320, unless otherwise indicated. Thus, for purposes of brevity, thediscussion will focus more on differences with these examples. Each oneof the plurality of cover sheet probes 310 may include a correspondingone of the tips 312 extending from a head 416. The core 210 may includea plurality of the pedestals 212. The plurality of cover sheet probes310 may form a pattern. The pattern of the cover sheet probes 310 maymatch a pattern of pedestals 212. The corresponding tip 312 of each oneof the cover sheet probes 310 may abut against the outer surface 222 ofthe cover sheet 220. The corresponding tip 312 of each one of the coversheet probes 310 may each align with one of the pedestals 212. One ormore of the inner pedestal probes 320 may abut a predetermined area ofthe core 310 to create the conductive electrical path 314 through thecore 210 from the cover sheet probes 310. The inner pedestal probes 320may align with an area of the core 210 abutting the inner surface 224 ofthe cover sheet 220 opposite the outer surface 222 abutted to the coversheet probe 310. The inner pedestal probe 320 may, for example, beplaced in the cooling channel 240 of the core 210 such that the innerpedestal probe 320 contacts the portion of the inner wall 242 opposite alocation of one of the pedestals 212 being coupled with the interiorwall 242.

The methods, devices, processing, circuitry, and logic described abovemay be implemented in many different ways and in many differentcombinations of hardware and software. For example, all or parts of theimplementations may be circuitry that includes an instruction processor,such as a Central Processing Unit (CPU), microcontroller, or amicroprocessor; or as an Application Specific Integrated Circuit (ASIC),Programmable Logic Device (PLD), or Field Programmable Gate Array(FPGA); or as circuitry that includes discrete logic or other circuitcomponents, including analog circuit components, digital circuitcomponents or both; or any combination thereof. The circuitry mayinclude discrete interconnected hardware components or may be combinedon a single integrated circuit die, distributed among multipleintegrated circuit dies, or implemented in a Multiple Chip Module (MCM)of multiple integrated circuit dies in a common package, as examples.

Accordingly, the circuitry may store or access instructions forexecution, or may implement its functionality in hardware alone. Theinstructions may be stored in a tangible storage medium that is otherthan a transitory signal, such as a flash memory, a Random Access Memory(RAM), a Read Only Memory (ROM), an Erasable Programmable Read OnlyMemory (EPROM); or on a magnetic or optical disc, such as a Compact DiscRead Only Memory (CDROM), Hard Disk Drive (HDD), or other magnetic oroptical disk; or in or on another machine-readable medium. A product,such as a computer program product, may include a storage medium andinstructions stored in or on the medium, and the instructions whenexecuted by the circuitry in a device may cause the device to implementany of the processing described above or illustrated in the drawings.

The implementations may be distributed. For instance, the circuitry mayinclude multiple distinct system components, such as multiple processorsand memories, and may span multiple distributed processing systems.Parameters, databases, and other data structures may be separatelystored and managed, may be incorporated into a single memory ordatabase, may be logically and physically organized in many differentways, and may be implemented in many different ways. Exampleimplementations include linked lists, program variables, hash tables,arrays, records (e.g., database records), objects, and implicit storagemechanisms. Instructions may form parts (e.g., subroutines or other codesections) of a single program, may form multiple separate programs, maybe distributed across multiple memories and processors, and may beimplemented in many different ways.

In some examples, each unit, subunit, and/or module of the system mayinclude a logical component. Each logical component may be hardware or acombination of hardware and software. For example, each logicalcomponent may include an application specific integrated circuit (ASIC),a Field Programmable Gate Array (FPGA), a digital logic circuit, ananalog circuit, a combination of discrete circuits, gates, or any othertype of hardware or combination thereof. Alternatively or in addition,each logical component may include memory hardware, such as a portion ofthe memory, for example, that comprises instructions executable with theprocessor or other processors to implement one or more of the featuresof the logical components. When any one of the logical componentsincludes the portion of the memory that comprises instructionsexecutable with the processor, the logical component may or may notinclude the processor. In some examples, each logical components mayjust be the portion of the memory or other physical memory thatcomprises instructions executable with the processor or other processorto implement the features of the corresponding logical component withoutthe logical component including any other hardware. Because each logicalcomponent includes at least some hardware even when the includedhardware comprises software, each logical component may beinterchangeably referred to as a hardware logical component.

A second action may be said to be “in response to” a first actionindependent of whether the second action results directly or indirectlyfrom the first action. The second action may occur at a substantiallylater time than the first action and still be in response to the firstaction. Similarly, the second action may be said to be in response tothe first action even if intervening actions take place between thefirst action and the second action, and even if one or more of theintervening actions directly cause the second action to be performed.For example, a second action may be in response to a first action if thefirst action sets a flag and a third action later initiates the secondaction whenever the flag is set.

Each component may include additional, different, or fewer components.For example, the gas turbine engine 100 may include additionalcomponents such as intercoolers. The dual wall turbine blade 112 mayinclude components not shown, such as a platform and/or shank.Additionally, the system 300 may be implemented with additional,different, or fewer components. The logic illustrated in the flowdiagrams may include additional, different, or fewer operations thanillustrated. The operations illustrated may be performed in an orderdifferent than illustrated.

In addition to the parameters 342 previously discussed and the examplevalues in FIG. 12, the operational parameters 342 may include additionalsettings. In some examples, these parameters 342 may vary or be set to apreferable range. For example, shown in FIG. 13, two parameters 342 maybe critical parameters. One critical parameter is that the percentage ofbonding current (indicated, for one example, as weld current in thefigures) must be in excess of 50%. Bonding current may, for example, berelated to electrical current 346. The second critical parameter is thatthe time of bonding must be a fairly short time period, for example, 30to 60 seconds, in order to prevent melting and expulsion that may deformthe cover sheet 220 and/or surrounding pedestals 212 not targeted forbonding. Bonding time may, for example, refer to the amount of time theelectrical current 346 flows across the conductive electrical path 314between the cover sheet probe 310 and the inner pedestal probe 320.

In another example, additional trials were conducted to provide a moredetailed investigation of the effects of the percentage of bonding heat(indicated, for one example, as weld heat in the figures), bonding time,and up-slope parameters, for example start up-slope and/or up-slopetime. The example parameters for the trials are provided below in FIG.14 for the evaluation of heat (for example preheat, preheat time, and/orweld heat as shown in the figure), bonding time, up-slope time, andpreheat time.

The results in FIG. 14 indicate that bonding heat percentage and bondingtime have much larger effects on the integrity of the bond than up-slopetime or preheat time. The data tends to indicate that bonding heatpercentage should preferably be held in the range of 50% to 70% in orderto provide a good bond between surfaces with little or no melting.Bonding heat percentage may be related to electrical current 346,electrical voltage 348, and/or the resistance of the materials beingbonded. The data also indicates that bonding time should preferably beheld to relatively low values, for example, below 90 cycles, in order toprevent melting. When the bonding time data from FIG. 13 is combinedwith that of FIG. 14, it indicates that bonding time should preferablybe held to less than 60 cycles. The data from FIG. 13 indicates that, inone example, melting began at approximately 60 cycles. Therefore itwould tend to suggest that bonding time should preferably be heldbetween 30 and 50 cycles.

In another example, additional samples were manufactured to evaluate therange of acceptable bonding heat in further detail via metallography andshear testing. The parameters 342 used to generate these samples andassociated data are provided in FIG. 15 for investigation of bondingheat percentage and associated shear test results.

The results shown in FIG. 15 indicate that, in one example, 70% bondingheat produces borderline results with possible melting and expulsion.There is some variability at 70% bonding heat, as shown by themetallography results versus the shear test results. The parameters 342that may have contributed to this variability include the applied load,the relative degree of mating of the faces to be bonded, for example,the surface 250 of the pedestals 212 and the inner surface 224 of thecover sheet 220, as well as the amount of Ni flashing present on thefaces to be bonded. The effects of these items will be discussed laterin the report.

In another example, additional experiments were conducted investigatingvery short bond times with the aim of producing successful diffusionbonds with minimal exposure to oxidation of the bond faces. Theparameters 342 used for these trials and the results are shown in FIG.16. The data indicates that bonding becomes very sensitive with cyclesthat are on the order of 1/60^(th) of a second. Extremely short timesappear to lack robustness and may be even more sensitive when actualmanufacturing variability (pedestal size, surface condition, etc.) isintroduced. This indicates short cycle times of 1/60^(th) of a second orshorter would not be a valid approach.

In another example, additional testing was conducted to evaluate theroom temperature shear strength of bonds produced in the preferablerange of 50% to 70% bonding heat. The parameters 342 evaluated and therespective test results are shown in FIG. 17. In one example, theresults indicate that 70% bonding heat produces a slightly larger bondarea (using round bonding probes, for example bonding probe 410 shown inFIG. 7) and also a slightly higher ultimate shear strength than a lowerpercentage of bonding heat, for example 50-60%. The bond area may referto, for example, the nugget size indicated in the figures.

The data shown in FIG. 17 is very good considering that commercialliterature quotes a yield strength on base metal of HA230 as in the 35ksi to 40 ksi range. The data shown in FIG. 17 represents actualresistance bonding of the Ni-flashed surface without any meltingoccurring.

When considering the relatively brief bond cycle utilized and the factthat no melting occurs, questions arose concerning the elevatedtemperature strength of the bonds. Therefore, in another example,additional specimens for shear testing were manufactured for 60%, 70%,and 80% bonding heat. In one example, these specimens were designatedfor 1144.261 K shear testing with the exception of several 80% bondingheat specimens which would be utilized for generating room temperatureshear data for comparison to the data provided in FIG. 17. Theparameters 342 utilized and associated results are provided in FIG. 18.

The data indicates that a bonding heat percentage of 70% produces asignificant increase in elevated temperature shear strength as comparedto a bonding heat percentage of 60%. The data also indicates that 80%bonding heat produces shear properties similar to that of the bondsproduced in the preferable range of 50% to 70%, but also producesunacceptable melting and expulsion into the flow channels 216. Ingeneral this data indicates that the repair process should preferableuse 70% bonding heat in order to produce the best possible bondproperties without melting or expulsion.

An additional question arose as to the basic inspectability of thebonds, for example, for NDT and/or NDE repair purposes. In one example,un-bonded component sheets of lamilloy were bonded in a number ofdifferent locations utilizing different parameters 342. The bonded sheetwas then NDE inspected, for example, by the bonding system 300. Theparameters 342 utilized to bond the various areas, for example thesurface area 250 of the pedestal 212 and the inner surface 224 of thecover sheet 220, are provided in FIG. 19. In one example, the parameters16N, 17N, 18N, 19N, and 20N were utilized to bond the cover sheets 220in a number of different locations. These parameters correspond to 60%,70%, 75%, and 80% bonding heat. All bonds were detectable duringinspection, this demonstrated basic inspectability. More detaileddiscussion of NDE inspectability and the detectability of melting orwicked channels will be discussed later in this report.

FIG. 19 shows one example of the parameters 342 used for bonding thecover sheet 220.

In one example, trials were then conducted with rectangular probes, forexample, bonding probe 410 shown in FIG. 4, scaling the applied stressand/or load down from that of the round probe, for example, bondingprobe 410 shown in FIG. 7. The parameters 342 used for the first set oftrials are provided in FIG. 20. The results indicate that all samplesillustrated varying levels of melting. Some examples illustrated theonset of melting while others illustrated full melting.

In one example, the initial trials were then repeated using a higherload in order to insure full contact of the mating faces, for examplethe surface area 250 of the pedestal 212 and the inner surface 224 ofthe cover sheer 220. The results from these example trials are shown inFIG. 21. The results indicate that proper loading is critical. Loadingmay, for example, refer to pressing force 370. The data indicates thatwhen using proper loading, probes 410 of material Cu—Zr, a bondingcurrent in the range of 60% to 70%, and a bonding time between 30 and 60cycles, preferable results will be produced. In one example, theparameters shown in FIG. 20 produce microstructures. The microstructurerepresents bond #4 and bond #5 from FIG. 21. All other bonds weremetallographically evaluated and demonstrated varying degrees of graingrowth in the bonded interlayer of Ni flashing.

To clarify the use of and to hereby provide notice to the public, thephrases “at least one of <A>, <B>, . . . and <N>” or “at least one of<A>, <B>, . . . <N>, or combinations thereof” or “<A>, <B>, . . . and/or<N>” are defined by the Applicant in the broadest sense, superseding anyother implied definitions hereinbefore or hereinafter unless expresslyasserted by the Applicant to the contrary, to mean one or more elementsselected from the group comprising A, B, . . . and N. In other words,the phrases mean any combination of one or more of the elements A, B, .. . or N including any one element alone or the one element incombination with one or more of the other elements which may alsoinclude, in combination, additional elements not listed. Unlessotherwise indicated or the context suggests otherwise, as used herein,“a” or “an” means “at least one” or “one or more.”

While various embodiments have been described, it will be apparent tothose of ordinary skill in the art that many more embodiments andimplementations are possible. Accordingly, the embodiments describedherein are examples, not the only possible embodiments andimplementations.

The subject-matter of the disclosure may also relate, among others, tothe following aspects:

A first aspect relates to a bonding probe comprising: a body; anattachment end at a distal end of the body to couple the body to aresistance welder; a head at an opposite end of the body from theattachment end; a tip extending from the head to form a proximate end ofthe body, the tip including a contacting area having a predeterminedthree-dimensional (3D) contoured surface to align with athree-dimensional (3D) contoured outer surface of a 3D cover sheet of adual walled structure; and a cooling passageway providing a passagewayfor a flow of a cooling fluid, the cooling passageway extending from theattachment end, through the head, and into the tip.

A second aspect relates to the bonding probe of aspect 1, wherein thecontacting area is a predetermined shape to align with a surface area ofa pedestal abutting an inner surface of the 3D cover sheet, the innersurface of the 3D cover sheet being an opposing surface of the 3Dcontoured outer surface of the 3D cover sheet.

A third aspect relates to the bonding probe of any preceding aspect,wherein the pedestal is a first pedestal, wherein the predeterminedshape of the contacting area is dimensioned to extend on the 3Dcontoured outer surface of the 3D cover sheet to align with asurrounding peripheral edge of the surface area of the pedestal orextend beyond the surrounding peripheral edge of the surface area of thepedestal by less than a predetermined percentage of a distance betweenthe first pedestal and a second pedestal adjacent to the first pedestal.

A fourth aspect relates to the bonding probe of any preceding aspect,wherein the tip is a deformable metal alloy having a two-way shapememory effect with a greater degree of elasticity/malleability than amaterial forming the 3D cover sheet.

A fifth aspect relates to the bonding probe of any preceding aspect,wherein the deformable metal alloy of the tip has a greater yieldstrength than the material forming the 3D cover sheet.

A sixth aspect relates to the bonding probe of any preceding aspect,wherein the passageway provided by the cooling passageway is aserpentine shaped passageway, the cooling passageway further including acontact area cavity disposed in the tip, the contact area cavitypositioned in the tip to align with and extend along the predeterminedthree-dimensional (3D) contoured surface of the contacting area toconduct heat away from the contacting area and into the cooling fluidpresent in the contact area cavity.

A seventh aspect relates to the bonding probe of any preceding aspect,wherein a wall of the contact area cavity is substantially parallel withthe predetermined three-dimensional (3D) contoured surface of thecontacting area.

An eighth aspect relates to the bonding probe of any preceding aspect,wherein the tip includes planar side walls extending away from the headto peripheral edges defining the contacting area.

A ninth aspect relates to the bonding probe of any preceding aspect,wherein the tip comprises machined sidewalls extending to one or moreperipheral edges surrounding and defining the contact area.

A tenth aspect relates to a bonding probe comprising: a tip; a headcomprising a first end and a second end, the first end coupled to thetip, the tip extending away from the head; an insulator coupled to thesecond end of the head; an attachment end coupled to the insulator, theattachment end to electrically couple the tip to a resistance welder; acooling passageway extending through the bonding probe, the coolingpassageway configured to provide a path for a flow of a cooling fluid;and a contacting area disposed on the tip, the contacting areaincluding: a surrounding peripheral edge defining a perimeter of thecontacting area, the perimeter of the contacting area corresponding to apredetermined area of a three-dimensional (3D) contoured outer surfaceof a 3D cover sheet of a dual walled structure, and a predeterminedthree-dimensional (3D) contoured surface to align with thethree-dimensional (3D) contoured outer surface within the predeterminedarea.

An eleventh aspect relates to the bonding probe of aspect 10, whereinthe tip comprises planar side walls extending from the first end of thehead and terminated by the contacting area.

A twelfth aspect relates to the bonding probe of any preceding aspect,wherein the contacting area is a predetermined shape that is inalignment with a surface area of a pedestal abutting an inner surface ofthe 3D cover sheet, the inner surface of the 3D cover sheet being anopposing surface of the 3D contoured outer surface of the 3D coversheet.

A thirteenth aspect related to the bonding probe of any precedingaspect, wherein the pedestal is a first pedestal, wherein thesurrounding peripheral edge of the tip aligns with a surroundingperipheral edge of the surface area of the pedestal or extends beyondthe surrounding peripheral edge of the surface area of the pedestal byless than a predetermined percentage of a distance between the firstpedestal and a second pedestal directly neighboring, and included in apredetermined repeating pattern of pedestals, that includes the firstpedestal.

A fourteenth aspect relates to the bonding probe of any precedingaspect, wherein the cooling passageway extends into the tip.

A fifteenth aspect relates to the bonding probe of any preceding aspect,wherein the cooling passageway extends into the tip from the head incloser proximity to a first planar side wall of the tip, extendsparallel to the contacting area, and extends into the head from the tipin closer proximity to a second planar side wall of the tip.

A sixteenth aspect relates to the bonding probe of any preceding aspect,wherein the head comprises multiple heads, tip comprises multiple tips,and the attachment end is a single attachment end, the multiple headscoupled to the single attachment end, and each head is coupled to arespective one or more of the tips.

A seventeenth aspect relates to the bonding probe of any precedingaspect, wherein the bonding probe corresponds to a pull plane of a 3Dcontoured dual wall structure.

An eighteenth aspect relates to a bonding probe comprising: a body; anattachment end included in the body and configured to couple the body toa resistance welder; a head coupled with the body; a tip extending fromthe head to form an end of the body opposite the attachment end, the tipincluding a contacting area having a predetermined three-dimensional(3D) contoured surface; and a cooling passageway providing a path for aflow of a cooling fluid, wherein the cooling passageway includes a tipinlet passage and a tip outlet passage, wherein a contacting area cavityfluidly connects the tip inlet passage and tip outlet passage, thecontacting area cavity substantially parallel to the contacting area,wherein, during operation of the resistance welder, the cooling fluid inthe tip inlet passage is cooler than cooling fluid in the contactingarea cavity and the cooling fluid in the tip outlet passage is warmerthan the cooling fluid in the contacting area cavity.

A nineteenth aspect relates to the bonding probe of aspect 18, whereinat least one of the tip inlet passage and the tip outlet passage extendsthrough the tip such that at least one of a section of the tip inletpassage and a section of the tip outlet passage extends substantiallyparallel to the contacting area cavity within the tip.

A twentieth aspect relates to the bonding probe of any preceding aspect,wherein the tip comprises a rigid alloy member having planar side wallsextending from the head and terminating at the contacting area, whereinthe tip inlet passage is in closer proximity to a first planar side walland the tip outlet passage is in in closer proximity to a second planarside wall.

In addition to the features mentioned in each of the independent aspectsenumerated above, some examples may show, alone or in combination, theoptional features mentioned in the dependent aspects and/or as disclosedin the description above and shown in the figures.

What is claimed is:
 1. A bonding probe comprising: a body; an attachmentend at a distal end of the body to couple the body to a resistancewelder; a head at an opposite end of the body from the attachment end; atip extending from the head to form a proximate end of the body, the tipincluding a contacting area having a predetermined three-dimensional(3D) contoured surface to align with a three-dimensional (3D) contouredouter surface of a 3D cover sheet of a dual walled structure; and acooling passageway providing a passageway for a flow of a cooling fluid,the cooling passageway extending from the attachment end, through thehead, and into the tip.
 2. The bonding probe of claim 1, wherein thecontacting area is a predetermined shape to align with a surface area ofa pedestal abutting an inner surface of the 3D cover sheet, the innersurface of the 3D cover sheet being an opposing surface of the 3Dcontoured outer surface of the 3D cover sheet.
 3. The bonding probe ofclaim 2, wherein the pedestal is a first pedestal, wherein thepredetermined shape of the contacting area is dimensioned to extend onthe 3D contoured outer surface of the 3D cover sheet to align with asurrounding peripheral edge of the surface area of the pedestal orextend beyond the surrounding peripheral edge of the surface area of thepedestal by less than a predetermined percentage of a distance betweenthe first pedestal and a second pedestal adjacent to the first pedestal.4. The bonding probe of claim 1, wherein the tip is a deformable metalalloy having a two-way shape memory effect with a greater degree ofelasticity/malleability than a material forming the 3D cover sheet. 5.The bonding probe of claim 4, wherein the deformable metal alloy of thetip has a greater yield strength than the material forming the 3D coversheet.
 6. The bonding probe of claim 1, wherein the passageway providedby the cooling passageway is a serpentine shaped passageway, the coolingpassageway further including a contact area cavity disposed in the tip,the contact area cavity positioned in the tip to align with and extendalong the predetermined three-dimensional (3D) contoured surface of thecontacting area to conduct heat away from the contacting area and intothe cooling fluid present in the contact area cavity.
 7. The bondingprobe of claim 6, wherein a wall of the contact area cavity issubstantially parallel with the predetermined three-dimensional (3D)contoured surface of the contacting area.
 8. The bonding probe of claim1, wherein the tip includes planar side walls extending away from thehead to peripheral edges defining the contacting area.
 9. The bondingprobe of claim 1, wherein the tip comprises machined sidewalls extendingto one or more peripheral edges surrounding and defining the contactarea.
 10. A bonding probe comprising: a tip; a head comprising a firstend and a second end, the first end coupled to the tip, the tipextending away from the head; an insulator coupled to the second end ofthe head; an attachment end coupled to the insulator, the attachment endto electrically couple the tip to a resistance welder; a coolingpassageway extending through the bonding probe, the cooling passagewayconfigured to provide a path for a flow of a cooling fluid; and acontacting area disposed on the tip, the contacting area including: asurrounding peripheral edge defining a perimeter of the contacting area,the perimeter of the contacting area corresponding to a predeterminedarea of a three-dimensional (3D) contoured outer surface of a 3D coversheet of a dual walled structure, and a predetermined three-dimensional(3D) contoured surface to align with the three-dimensional (3D)contoured outer surface within the predetermined area.
 11. The bondingprobe of claim 10, wherein the tip comprises planar side walls extendingfrom the first end of the head and terminated by the contacting area.12. The bonding probe of claim 10, wherein the contacting area is apredetermined shape that is in alignment with a surface area of apedestal abutting an inner surface of the 3D cover sheet, the innersurface of the 3D cover sheet being an opposing surface of the 3Dcontoured outer surface of the 3D cover sheet.
 13. The bonding probe ofclaim 12, wherein the pedestal is a first pedestal, wherein thesurrounding peripheral edge of the tip aligns with a surroundingperipheral edge of the surface area of the pedestal or extends beyondthe surrounding peripheral edge of the surface area of the pedestal byless than a predetermined percentage of a distance between the firstpedestal and a second pedestal directly neighboring, and included in apredetermined repeating pattern of pedestals, that includes the firstpedestal.
 14. The bonding probe of claim 10, wherein the coolingpassageway extends into the tip.
 15. The bonding probe of claim 14,wherein the cooling passageway extends into the tip from the head incloser proximity to a first planar side wall of the tip, extendsparallel to the contacting area, and extends into the head from the tipin closer proximity to a second planar side wall of the tip.
 16. Thebonding probe of claim 10, wherein the tip comprises multiple tips andthe attachment end is a single attachment end, the head coupled to thesingle attachment end and each of the respective tips.
 17. The bondingprobe of claim 16, wherein the contacting area of the tips correspondsto a pull plane of a 3D contoured dual wall structure.
 18. A bondingprobe comprising: a body; an attachment end included in the body andconfigured to couple the body to a resistance welder; a head coupledwith the body; a tip extending from the head to form an end of the bodyopposite the attachment end, the tip including a contacting area havinga predetermined three-dimensional (3D) contoured surface; and a coolingpassageway providing a path for a flow of a cooling fluid, wherein thecooling passageway includes a tip inlet passage and a tip outletpassage, wherein a contacting area cavity fluidly connects the tip inletpassage and tip outlet passage, the contacting area cavity substantiallyparallel to the contacting area, wherein, during operation of theresistance welder, the cooling fluid in the tip inlet passage is coolerthan cooling fluid in the contacting area cavity and the cooling fluidin the tip outlet passage is warmer than the cooling fluid in thecontacting area cavity.
 19. The bonding probe of claim 18, wherein atleast one of the tip inlet passage and the tip outlet passage extendsthrough the tip such that at least one of a section of the tip inletpassage and a section of the tip outlet passage extends substantiallyparallel to the contacting area cavity within the tip.
 20. The bondingprobe of claim 19, wherein the tip comprises a rigid alloy member havingplanar side walls extending from the head and terminating at thecontacting area, wherein the tip inlet passage is in closer proximity toa first planar side wall and the tip outlet passage is in in closerproximity to a second planar side wall.